Side mounted temperature probes for pressware die sets

ABSTRACT

In a temperature controlled segmented die for forming pressed containers such as plates, trays, bowls or the like including a die segment with a forming surface and an outer movable annular die member there is provided a side mounted temperature probe which extends laterally around the movable annular die member and toward the forming surface of the die segment. The apparatus is particularly useful for forming pressed paperboard containers such as paper plates.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a divisional patent application U.S. Ser. No.09/653,572, filed Aug. 31, 2000, now U.S. Pat. No. 6,585,506, which wasbased on United States Provisional Application Ser. No. 60/153,096,filed Sep. 9, 1999. The priorities of the foregoing applications andpatent are hereby claimed.

TECHNICAL FIELD

The present invention relates to the temperature-controlled die sets forforming food serving disposable pressware containers, such as plates,bowls, trays and the like, and more particularly to a temperaturecontrolled die set utilizing a side mounted, flexible temperature probewhich is angled toward the forming surface of a die segment. Theapparatus of the present invention is particularly useful for formingplates and the like from paperboard blanks, where temperature controlnear the forming surfaces is particularly important.

BACKGROUND

Pressed containers, such as pressed paperboard containers includingplates, trays, bowls and the like are well known in the art. Typically,such articles are manufactured on an inclined die set having upper andlower halves. Illustrative in this regard is U.S. Pat. No. 5,249,946 toMarx assigned to the assignee of the present invention. Referring to the'946 patent, a typical product is manufactured by way of feeding acontinuous paperboard web into a cyclically operating blanking section.The forming section includes a plurality of reciprocating upper diehalves opposing, in facing relationship, a plurality of lower diehalves. The upper die halves are mounted for reciprocating movement in adirection that is oblique or inclined with respect to the verticalplane. The blanks, after cutting, are gravity fed to the inclined lowerdie halves in the forming section.

Particular forming dies and processes for making pressed paperboardproducts are likewise well known. Most typically, dies sets for formingpaperboard containers include a male or punch die half and a female diehalf. Typically, the punch half is reciprocally mounted with respect toits opposing die half and both die halves are segmented. One or moreportions of the die halves may be spring-biased if so desired, and theparticular geometry of the die will depend upon the product desired. Inthis regard, there is shown in U.S. Pat. No. 4,832,676 to Johns et al.an apparatus for forming a compartmented paperboard plate. The diesillustrated in the '676 patent includes spring-biased segments as wellas pressure rings on the punch half and draw rings about the opposingplate. The particular apparatus further includes an articulated, fullarea knock-out.

Forming operations can be somewhat critical in order to produce qualityproduct at the desired rates. In this respect U.S. Pat. No. 4,721,500 toVan Handle et al. is informative. Note also U.S. Pat. No. 4,609,140 toVan Handle et al. The '140 patent provides a general description of oneknown forming method as will be appreciated from FIG. 3 thereof. FIG. 3shows a cross section of the upper die half and lower die half which areutilized to press a flat, circular paperboard blank into the shape ofthe plate. The construction of the die halves and the equipment on whichthey are mounted is substantially conventional; for example, as utilizedon presses manufactured by the Peerless Manufacturing Company. Tofacilitate the holding and shaping of the blank, the die halves aresegmented in the manner shown. The lower die has a circular base portionand a central circular platform which is mounted to be moveable withrespect to the base. The platform is cam operated in a conventionalmanner and urged toward a normal position such that it's flat topforming surface is initially above the forming surface of the base. Theplatform is mounted for sliding movement to the base, with the entirebase itself being mounted in a conventional manner on springs. Becausethe blank is very tightly pressed at the peripheral rim area, moisturein the paperboard which is driven therefrom during pressing and theheated dies cannot readily escape. To allow the release of thismoisture, at least one circular groove is provided in the surface of thebase which vents to the atmosphere through a passageway. Similarly, thetop die half is segmented into an outer ring portion, a base portion anda central platform having a flat forming surface. The base portion hascurved, symmetrical forming surfaces and the outer ring has curvedforming surfaces. The central platform in the outer ring are slidinglymounted to the base and biased by springs to their normal position shownin FIG. 3 in a commercially conventional manner. The top die half ismounted to reciprocate toward and away from the lower die half. In thepressing operation, the blank is first laid upon the flat formingsurface, generally underling the bottom wall portion of the plate to beformed, and the forming surface makes first contact with the top of theblank to hold the blank in place as the forming operation begins.Further downward movement of the top die half brings the spring-biasedforming surfaces of the outer ring into contact with the edges of theblank to begin to shape the edges of the blank over the underlyingsurfaces in the areas which will define the overturned rim of thefinished plate. However, because the ring is spring-biased thepaperboard material in the rim area is not substantially compressed ordistorted by the initial shaping since the force applied by the formingsurfaces is generally light and limited to the spring force applied tothe ring. Eventually, the top die half moves sufficiently far down sothat the platform segments and the ring are fully compressed such thatthe adjacent portions of the forming surfaces are coplanar. In aconventional manner the die halves are heated with electrical resistanceheaters and the temperature of the die halves is controlled to aselected level by monitoring the temperature of the dies withthermistors mounted in the dies as close as possible to the formingsurfaces.

For paperboard plates stock of conventional thicknesses ie. in the rangeof from about 0.010 to about 0.040 inches, the spacing between the upperdie surface and the lower die surface decline continuously from thenominal paperboard thickness at the center to a lower value at the rim.

The springs upon which the lower die half is mounted are typicallyconstructed such that the full stroke of the upper die results in aforce applied between the dies of from about 6000 to 8000 pounds.

The paperboard which is formed into the blanks is conventionallyproduced by a wet laid paper making process and is typically availablein the form of a continuous web on a roll. The paperboard stock ispreferred to have a basis weight in the range of from about 100 poundsto about 400 pounds per 3000 square foot ream and a thickness or caliperin the range of from about 0.010 to about 0.040 inches as noted above.Lower basis weights and caliper paperboard is preferred for ease offorming and for saving feedstock costs. Paperboard stock utilized forforming paper plates is typically formed from bleached pulp furnish, andis usually double clay coated on one side. Such paperboard stockcommonly has a moisture (water content) varying from about 4.0 to about8.0 percent by weight.

The effect of the compressive forces at the rim is greatest when theproper moisture conditions are maintained within the paperboard: atleast 8% and less than 12% water by weight, and preferably 9.5 to 10.5%.Paperboard in this range has sufficient moisture to deform underpressure, but not such excessive moisture that water vapor interfereswith the forming operation or that the paperboard is too weak towithstand the high compressive forces applied. To achieve the desiredmoisture levels within the paperboard stock as it comes off the roll,the paperboard is treated by spraying or rolling on a moisteningsolution, primarily water, although other components such as lubricantsmay be added. The moisture content may be monitored with a hand heldcapacitive type moisture meter to verify that the desired moistureconditions are being maintained. It is preferred that the plate stocknot be formed for at least six hours after moistening to allow themoisture within the paperboard to reach equilibrium.

Because of the intended end use of the paper plates, the paperboardstock is typically coated on one side with a liquid proof layer orlayers. In addition, for esthetic reasons, the paper plate stock isoften initially printed before being coated. As an example of typicalcoating material, a first layer of polyvinyl acetate emulsion may beapplied over the printed paperboard with a second layer ofnitrocellulose lacquer applied over the first layer. The plate stock ismoistened on the uncoated side after all of the printing and coatingsteps have been completed. In a typical forming operation, the web ofpaperboard stock is fed continuously from a roll through a cutting dieto form the circular blanks which are then fed into position between theupper and lower die halves. The dies halves are heated as describedabove, to aid in the forming process. It has been found that bestresults are obtained if the upper die half and lower diehalf—particularly the surfaces thereof—are maintained at a temperaturein the range of from about 250° F. to about 320° F., and most preferablyat about 300° F.±10° F. These die temperatures have been found tofacilitate the plastic deformation of paperboard in the rim areas if thepaperboard has the preferred moisture levels. At these preferred dietemperatures, the amount of heat applied to the blank is apparentlysufficient to liberate the moisture within the blank under the rim andthereby facilitate the deformation of the fibers without overheating theblank and causing blisters from liberation of steam or scorching theblank material. It is apparent that the amount of heat applied to thepaperboard will vary with the amount of time that the dies dwell in aposition pressing the paperboard together. The preferred dietemperatures are based on the usual dwell times encountered for normalproduction speeds of 40 to 60 pressings a minute, and commensuratelyhigher or lower temperatures in the dies would generally be required forhigher or lower production speeds, respectively.

As will be appreciated by one of skill in the art, the knock-outs areimportant for holding the container blank on center during formation andfor separating the finished product from the die halves, particularlyduring high speed operation. The mechanical features can be furtheraugmented pneumatically as is disclosed in U.S. Pat. No. 4,755,128 toAlexander et al. Other patents of interest include: U.S. Pat. No.4,435,143 to Dempsey; U.S. Pat. No. 5,041,071 to Reasinger et al.; andU.S. Pat. No. 4,778,439 to Alexander.

A temperature sensor such as a thermocouple, thermistor, or a resistivetemperature device (“RTD”) can be inserted externally, that is fromoutside of the die set periphery straight into the die or punch halfforming base to give a relative temperature measurement. This sensingmethod does not provide a realistic measurement of the forming surfacetemperature since the sensor is typically several inches away. Widerswings in actual forming surface temperatures can exist with such anexternally mounted temperature sensor due to the time lag resulting fromthe distances between the heating element, the forming surface, and thesensors. A peripherally mounted temperature sensor can be easilyinstalled or replaced if the die set is hot and mounted in a formingpress, but provides relatively poor forming surface temperature controland consistency. Thus formed, pressware products will have largerdeviations in formation, heat pressing and correspondingstrengths/rigidity. While a peripherally mounted temperature probe is alow cost simple method, it is not preferred due to the lack of controland consistency.

Another method which is commonly used involves internally inserting atemperature probe into a segmented die directly above the formingsurface in an axial position above the area desired to be measured. Atemperature sensor such as a thermocouple, thermistor or RTD can beinserted axially (internally from within the die set towards the die orpunch die surface) to provide improved temperature control andconsistency. The temperature sensor typically is inserted internally toavoid interference with the moving components of the die set including,for example, a pressure and draw ring. Formed pressware products willhave more consistent formation, pleat pressing and correspondingstrength/rigidity. However, the sensor must be installed or replacedwhen the die half is out of the forming press. This is a safety concernwhen the heavy die set is hot it must be handled/lifted out of and intothe press. Excessive machine down time is experienced using thisinternal or axially mounted method. Up to twelve thermocouples in totalcan be used in a typical forming press to provide independenttemperature contrtol for all of the plurality of die and punch halves.The chance of a thermocouple failure are thus substantially increased.All the forming lanes of the press must be shut down to replace onefailed internally mounted thermocouple resulting in significant machinedown time, loss of production and non-productive man hours. Product costincreases and product quality decreases if a failed thermocouple is notreplaced immediately.

SUMMARY OF INVENTION

This invention relates to the application of a side mounted temperaturesensor such as thermocouples, thermistors, RTD, and the like in matchedmetal pressware die sets for the conversion of food service disposablearticles such as plates, bowls, trays, and platters to improve ease ofinstallation and replacement upon failure of the temperature sensors.The side mounted temperature sensors are easier to install and replaceupon failure and result in less machine downtime and less non-productiveman hours, thus increasing forming productivity (product output) andreducing product cost while maintaining a consistent, quality pressedproduct.

Accurate temperature measurement is essential in the production ofconsistent quality pressed paperboard products such as plates, bowls,oval platters and trays. The moistened paperboard is cut into blanks(which may be scored) and formed between two heated matched metalforming die halves (die and punch) which are closed under pressure for agiven dwell period; typically on the order of 1 second or less. Thepaperboard container in the blank is folded into pleats during theforming and is dried to conform to the shape of the die set. Thecombination of moisture, heat and pressure is necessary to obtain thefinal product shape and to press the paperboard pleats. Final productstrength/rigidity is determined from this process.

The temperature measurement sensor should ideally be as close aspossible to the forming surface that contacts the paperboard and pressesthe paperboard pleats to maintain consistency and control. Thetemperature measurement sensors must be inserted in a manner such thatthey do not interfere with the moving die set components such as thedraw ring, and pressure ring, and so forth, that are necessary tocontrol paperboard gathering and plate formation.

The temperature measurement sensors typically connect to a controllerthat turns on and off power to heating components (ring, tubular, castheaters, and so forth) which are internally located in the die sethalves. The controller will heat or cool the die set towards the desiredprocess set point based on the input from the corresponding temperaturemeasurement sensors. One temperature measurement sensor and onecontroller is typically necessary for each die and punch half across theforming press. A forming press may contain up to six die and punchcombinations, thus requiring a total of twelve temperature sensors andtwelve controllers.

Temperature probes are available in a wide variety of styles, sizes,lengths, wire diameters, wire coverings, and so forth. The sensor styleswould include thermocouples of type J, K, T, E, R & S wire combinationsthat have two dissimilar metals in intimate contact to develop a voltagewhich depends on the temperature of the junction and the particularmetals used. The following Table correlates ANSI codes with the materialcombinations for thermocouples:

Materials and Polarities ANSI Code Positive Negative T Cu Constantan ENi-Cr Constantan J Fe Constantan K Ni-Cr Ni-Al R Pt-13% Rh Pt S Pt-10%Rh Pt

A resistive temperature device or “RTD” may include a wire-wound ceramicelement, wound with a purity-controlled platinum wire and are generallyavailable from sensor suppliers such as Watlow Gordon of Illinois. Soalso thermistors and RTD's, which are electrical conductors thatexperience a change in resistance with temperature, may be employed ifso desired.

The preferred side mounted temperature probes used in accordance withthe present invention are a J style (iron/constantan) sheath groundedjunction thermocouple with a spring loaded bayonet style fitting such asdescribed hereinafter. Particularly preferred temperature probes may beobtained from Watlow Gordon of Richmond, Ill., USA under a part no.10DJSGBO 43A which defines a construction code, 10=VAT (variableadjustable thermocouple) with 6 inch spring, sheath diameter (inchesD={fraction (3/16)} inch), calibration J=type J (iron/constantan), leadprotection S=fiberglass with stainless steel over braid (24 gaugestranded), junction G=grounded, round tip, sheath length (inches B=1),lead length=43 inches, termination/options A=standard, 2½ inch splitleads. A multiplicity of variations on the preferred type of probe arepossible for the side mount thermocouple within the spirit and scope ofthe present invention.

In accordance with the invention, a temperature sensor such as athermocouple or thermistors can be inserted externally, that is, fromthe sidewall outside of the die set without interfering with any movingdie set components such as the pressure or draw ring and bent around acorner towards the die or punch forming surface to provide improvedtemperature control and consistency. The die set is especially designedto allow space for the temperature sensors to be inserted without anyinterference. This may involve increasing the overall die set height. Ina preferred embodiment, a removable machined housing component ismounted on to the die or punch base to ease the cornering of thethermocouple during insertion or removal. This housing is mounted withtwo socket head cap screws that can be easily and safely removed from ahot die set. Clearance holes are machined through and into the die baseso that the preferred thermocouple and spring overwrap can be easilyinserted without interference. The rounded tip is ideally the only partof the thermocouple probe which touches the die set near the formingsurface. The bayonet fitting must be adjusted/turned such as to providespring compression upon mounting to ensure that the tip is biased intocontact with the die set metal near the forming surface. This method ispreferred since it provides accurate and consistent temperature controlfor the pressware process without the necessity to remove the die set toinstall or replace temperature sensors. The side mounted temperaturesensors can be replaced in a hot die set safely in minutes withoutremoving the die set, resulting in less machine down time, lower costproduction and minimal product cost impact. The side mounted temperaturesensor technique is easily implemented as would be appreciated from thedetailed description hereinafter.

Described more generally, there is provided by way of the presentinvention in a temperature controlled, segmented die for forming presscontainers such as plates, trays, bowls, and the like, mounted about anaxis of reciprocation and being provided with an outer annular diemember and a die segment with a forming surface, the outer die memberbeing moveable along the axis of reciprocation with respect to the diesegment and the forming surface along a stroke length proximate to theforming surface there is additionally provided a flexible temperatureprobe having a sensor tip inserted laterally into a sidewall of thesegmented die, outside of the stroke length of the annular member. Theflexible temperature probe extends laterally into the segmented die andis angled to extend toward the forming surface such that the sensor tipis within from about ½ to about {fraction (1/32)} inch of the formingsurface of the die segment. Typically the sensor tip is within fromabout {fraction (1/16)} to about ¼ inch of the forming surface; withinabout ⅛ inch of the forming surface being preferred.

In general the temperature probe can include a thermocouple such as aniron/constantan thermocouple, a thermistor or RTD. The temperature probepreferably includes means for biasing the temperature sensor tip towardthe forming surface such as a spring which is most preferably affixed toa retaining member or to the sidewall of the segmented die.

There is thus provided in another aspect of the present invention atemperature controlled segmented die half for forming press containerssuch as plates, bowls, trays and the like mounted about an axis ofreciprocation and including: (a) a die segment defining a formingsurface; (b) means for heating said die segment; (c) an outer annulardie assembly moveably mounted along the axis of reciprocation withrespect to the die segment and forming surface along a stroke lengthproximate to the forming surface; (d) a flexible temperature probe witha sensor tip; (e) a temperature controller coupled to said means forheating said base plate and said flexible temperature probe; and (f)means for securing said flexible temperature probe to the segmented diesuch that the flexible temperature probe is inserted laterally into thesidewall of the segmented die outside of the stroke length of the outerannular die member and the flexible temperature probe is angled toextend toward the forming surface of the die segment such that thesensor tip is within from about {fraction (1/32)} to about ¼ inch fromthe forming surface of the die segment.

Typically the sensor tip of the flexible temperature probe is withinfrom about {fraction (1/16)} to about ¼ inch of the forming surface;within about ⅛ inch of the forming surface of the base plate beingpreferred. In a most preferred embodiment a spring annularly surroundsthe flexible temperature probe and is connected to a retaining member ina form of a slotted cap affixed to both the spring of the flexibletemperature probe and wherein the slotted cap is lockingly engaged to apair of pins mounted on the temperature controlled segmented die, thatis a typical bayonet fitting as noted above.

In still yet another aspect of the invention there is provided a methodof forming a pressed container from a container blank comprising: (a)measuring the temperature with a temperature sensor in a segmented diemaintained about an axis of reciprocation, the die being provided withan annular outer member and a die segment with a forming surface, theouter annular die member being moveable along the axis of reciprocationwith respect to the base plate and forming surface along a stroke lengthproximate to the forming surface, the temperature sensor being disposedon the tip of a flexible temperature probe, inserted laterally in asidewall of the segmented die outside of the stroke length of the outerannular die member, the flexible temperature probe extending laterallyinto the segmented die and being angled to extend toward the formingsurface such that the sensor is within about from ½ to about {fraction(1/32)} inch from the forming surface of the die segment; (b) inresponse to the measurement of said temperature sensor, controllingtemperature of the die segment; and (c) forming the container bycontacting the forming surface with the container blank. The containerblank may be paperboard, plastic, paperboard/plastic composites and soforth such as are for disposable food serving containers. Mostpreferably the container blank is a paperboard container blank having athickness from about 0.008 to about 0.050 inches. Typically thepaperboard container blank has a moisture content of from about 8 toabout 12% by weight; with from about 8.5 to about 10.5% beingparticularly preferred. In general it is desirable to maintain thetemperature of the forming surface of the segmented die between about250° F. and 320° F. when forming a paperboard blank; between about 290°F. and 310° F. being particularly preferred.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described in detail below with reference to the variousfigures, wherein like numerals designate similar parts and wherein:

FIG. 1 is a schematic diagram illustrating the temperature probe of thepresent invention inserted to the upper and lower halves of a segmenteddie set in an open position;

FIG. 2 is a schematic diagram of the segmented die set of FIG. 1 in aclosed position illustrating the inventive temperature probe apparatus;

FIGS. 3(a) and 3(b) are details showing a particularly preferred methodof connecting a flexible temperature probe in accordance with thepresent invention; and

FIG. 4 is a detail illustrating a particularly preferred mode ofproviding a mounting cavity and channel for the flexible temperatureprobe of the present invention; and

FIG. 5 is a block diagram illustrating the connections between atemperature controller, the inventive temperature probes, and theheating coils located in the die segments of the die halves illustratedin FIGS. 1 and 2. The controller circuitry may also include thenecessary relays, switches, fuses and the like typically used for such aheating application.

DETAILED DESCRIPTION

The invention is described in detail below with reference to the variousfigures which illustrate specific embodiments of the present invention.Such description and exemplification is for purposes of illustrationonly and in no way limits the spirit and scope of the present inventionwhich is set forth in the appended claims. Inasmuch as the presentinvention is an improvement to existing pressware die sets and suchapparati, the invention will be described with reference to thedifferences between the present invention and existing equipment. Inthis regard, the following United States Patents are illustrative of thestate of the art and known systems:

U.S. Pat. No. 5,249,946;

U.S. Pat. No. 4,832,676;

U.S. Pat. No. 4,721,500;

U.S. Pat. No. 4,609,140;

the disclosures of which are hereby incorporated into this descriptionin their entirety by reference.

Referring now to FIGS. 1 through 5 the invention will now be describedwith reference to particular embodiments thereof.

There is shown in FIGS. 1 and 2 a metal pressware die set 10 whichincludes an upper die half (sometimes referred to in the art as thepunch) 12 and a lower die half (sometimes referred to in the art as thedie) 14. Both halves 12, 14 are segmented pressware dies as will beappreciated from the discussion which follows. Die half 12 and die half14 are mounted about an axis of reciprocation 16 in facing relationshipas shown. Die half 12 comprises generally of an upper base plate 18provided with a knock-out 20. There is additionally provided an annularpressure ring 22 as well as heating coils 24. Base plate 18 is providedwith forming surfaces such as surface 26 which is used to form thesidewall of a paperboard pressware product. It is at such surfaces thattemperature control is particularly important as will be appreciated byone of skill in the art. There may also be provided a plurality ofsprings, such as spring 28 can be used to bias the various parts.Typically, between 4 and 8 springs are used to individually bias thevarious parts. Likewise, knock-out 20 may be spring biased if sodesired. It can be appreciated by one skilled in the art that thevarious parts of the segmented die such as pressure ring 22 andknock-out 20 are capable of movement independently of the other parts ofthe segmented die such as plate 18. Pressure ring 22 makes itparticularly difficult to measure directly the temperature at surface 26of base plate 18 unless one utilized an internal temperature probesystem such as that known in the prior art as described hereinabove. Inaccordance with the invention, there is provided an angled flexibletemperature probe 30 that extends from the sidewall in a transversedirection as shown, that is, transverse being substantiallyperpendicular to the axis of reciprocation about which the die ismounted and is angled towards forming surface 26 so that the tip 34 ofthe temperature probe upon which the temperature sensor is located, isin proximity to surface 26. As will be appreciated hereinafter, pressurering 22 reciprocates about a stroke length indicated at 36, such that itis not possible to have a straight probe mounted on the die half 12approach surface 26 in close proximity.

On the lower half of FIG. 1 there is shown the lower half (die) of apressware die set which comprises a base plate 38 having a formingsurface 40 as well as a knock-out 42 and a draw ring shown at 44. It isadditionally provided with heating coils in 46 and a plurality ofsprings, such as spring 48 which may be used to bias the particulardesired segment of the die half if so desired. Typically, between 4 and8 springs are used to individually bias the various parts. In accordancewith the present invention there is provided an angled, flexible probe50 extending from the sidewall 52 of the die half toward forming surface40 of base plate 38. Here again due to the fact that draw ring 44 movesover a stroke length 54, it is not possible for a straight temperatureprobe to come into close proximity of forming surface 40 withoutinterfering with the operation of the segmented die. Thus, in accordancewith the present invention there is provided an angled flexibletemperature probe which can be in close proximity, i.e., {fraction(1/32)} to ½ of an inch of the forming surface without the need to gothrough the top or bottom surface of the die half which typically needsto be mounted on a press so that it is not readily accessible during useas noted above.

FIG. 2 is a diagram showing the die set of FIG. 1 as it would appearduring the forming step, that is, upon application of pressure to apaperboard blank, for example, where it can be seen that the outerannular rings such as pressure ring 22, and draw ring 44 (outer ringswhich are annular in nature) move from their rest position along thestroke lengths at 54 and 36. It can be seen that the temperature probes30 and 50 are transversely mounted on the sidewall of the die outside ofthe stroke length of both the rings 22 and 44 respectively. It shouldalso be appreciated that it is best to use a probe with a sensor tipsuch as tip 34 and a tip 56 such that the actual temperature sensor isclose to the area desired to be monitored for temperature. Likewise, itis desirable to see that the tip having the sensor is urged into contactwith the surface of the base plate as close as possible to a criticalforming surface such as surfaces 26, 40 during use. The particularlypreferred system for use in connection with the present invention is aspring loaded bayonet type of mounting system wherein spring loaded capssuch as caps 58 and 60 are used to position the flexible temperatureprobes as is better appreciated as shown in FIGS. 3a and 3 b. There isshown in FIG. 3a a slotted cap 58 as lockingly engageable about abayonet fitting 64 which is affixed to a sidewall such as sidewall 32 ofdie half 12. The cap is preferably affixed to a spring 66 as well as thetemperature probe 30 and wire 31 such that the tip of the probe can beurged against the surface of a channel such as channels 68, 70 in FIGS.1 and 2 in order to accurately measure temperature at the desiredlocation.

It is particularly preferred to utilize a removable plate defining acavity to install the inventive probe on a segmented die as will bedescribed in connection with FIG. 4. FIG. 4 shows the sidewall such assidewall 32 of a segmented die of the upper half of a segmented die setsometimes referred to as the punch half. There is provided in aparticularly preferred embodiment of the present invention a C-shapedretaining member 72 provided with bolt holes 74, 76 for bolting member72 to sidewall 32 as well as a central cavity 78 through which the probe30 along with a portion of spring 66 may pass. This way channel 68 isreadily available to an operator or technician wishing to thread probe30 down into the base plate of die half 12. It should be noted that amatching cavity 80 in the sidewall of the die half is provided so thatthe channel 60 may be readily fabricated by conventional techniques.

Turning finally to FIG. 5 it will be appreciated in accordance with theinvention that the temperature is monitored and the temperature formingsurfaces is controlled by conventional techniques. For example, theinput from a probe such as from probe 30, is provided to a controllersuch as controller 82 which compares the signal with a predeterminedvalue and will provide electrical power as appropriate to heating coilssuch as heating coils 24 in order to maintain the desired temperature atthe forming surface.

What is claimed is:
 1. A method of forming a pressed container from acontainer blank comprising: (a) measuring the temperature with atemperature sensor in a segmented die mounted about an axis ofreciprocation, said die being provided with an outer annular die memberand a die segment with a forming surface, said outer annular die memberbeing moveable along said axis of reciprocation with respect to said diesegment and forming surface along a stroke length proximate to saidforming surface, said temperature sensor being disposed on the tip of aflexible temperature probe inserted laterally in a sidewall of saidsegmented die outside of said stroke length of said outer annular diemember, said flexible temperature probe extending laterally into saidsegmented die in a first direction over a portion of its length andbeing angled toward said forming surface in a second direction over aportion of its length such that an inflection in the probe internal tothe segmented die set is defined between the first and second directionsand wherein said sensor on the tip of the probe is within from about ½to about {fraction (1/32)} inch of said forming surface of said diesegment; (b) in response to the measurements from said temperaturesensor, controlling the temperature of said die segment; and (c) formingsaid container by contacting said forming surface with said containerblank.
 2. The method according to claim 1, wherein said container blankis a paperboard container blank.
 3. The method according to claim 2,wherein said paperboard container blank has a caliper of from about0.008 inches to about 0.050 inches.
 4. The method according to claim 3,wherein said paperboard container blank has a moisture content of fromabout 8 to about 12% by weight.
 5. The method according to claim 2,wherein the temperature of said forming surface is maintained betweenabout 2500° F. and 350° F.
 6. The method according to claim 5, whereinthe temperature of said forming surface is maintained between 2900° F.and 310° F.
 7. A method of forming a pressed container from a containerblank comprising: (a) measuring the temperature with a temperaturesensor in a segmented die mounted about an axis of reciprocation, saiddie being provided with an outer annular die member and a die segmentwith a forming surface, said outer annular die member being moveablealong said axis of reciprocation with respect to said die segment andforming surface along a stroke length proximate to said forming surface,said temperature sensor being disposed on the tip of a flexibletemperature probe inserted laterally in a sidewall of said segmented dieoutside of said stroke length of said outer annular die member, saidflexible temperature probe extending laterally into said segmented diein a first direction over a portion of its length and being angledtoward said forming surface in a second direction over a portion of itslength such that an inflection in the probe internal to the segmenteddie set is defined between the first and second directions and whereinsaid sensor on the tip of the probe is proximate to said forming surfaceof said die segment; (b) in response to the measurements from saidtemperature sensor, controlling the temperature of said die segment; and(c) forming said container by contacting said forming surface with saidcontainer blank.
 8. The method according to claim 7, wherein saidcontainer blank is a paperboard container blank.
 9. The method accordingto claim 8, wherein said paperboard container blank has a caliper offrom about 0.008 inches to about 0.050 inches.
 10. The method accordingto claim 7, wherein said paperboard container blank has a moisturecontent of from about 8 to about 12% by weight.
 11. The method accordingto claim 9, wherein the temperature of said forming surface ismaintained between about 250° F. and 350° F.
 12. The method according toclaim 7, wherein the temperature of said forming surface is maintainedbetween 290° F. and 310° F.